时间:2019-01-22 作者:英语课 分类:英语时差8,16


英语课

 Fact: liquid water is heavier than air. Fact: clouds, which consist of water droplets 2 and ice crystals, seem to hover 3 in the air. One final fact: the water droplets in a typical cloud together weigh many tons. Which raises a question: how do clouds stay up in the sky?  Clouds form when warm, moist air rises to a greater altitude, causing it to expand and cool. Eventually, water vapor 4 in the cooled air condenses into the droplets that form clouds. The condensed droplets are on average roughly eight-one-hundred- thousandth of an inch across. In other words, a single droplet 1 is very, very small.


Despite their tiny size, the droplets still have mass and are therefore affected 5 by gravity. They are so small, however, that rising air keeps the water droplets aloft. The effect is similar to how dust appears to float in a shaft 6 of sunlight: although gravity works on the bits of dust, even the gentlest currents are enough to keep them swirling 7 around in the air.
Clouds, then, are not so much able to float as they are held up by surrounding air. In fact, the tiny cloud droplets do sink, but so slowly that it would take an hour for a single droplet to sink only one yard. And although the cumulative 8 weight of a cloud's droplets is many times that of the surrounding air, the droplets are spread out over a large enough area to render the gravitational pull on any single drop almost negligible. When the droplets become larger, gravity overcomes the dragging forces of the rising air and the droplets fall to the earth as rain.   

n.小滴,飞沫
  • The rate of droplet growth under different conditions can be evaluated.可以计算在不同条件下的云滴增长率。
  • The test results showed that increasing droplet size was associated with better stability.试验结果表明,增加液滴尺寸将使稳定性提高。
n.小滴( droplet的名词复数 )
  • Droplets of sweat were welling up on his forehead. 他额头上冒出了滴滴汗珠。 来自辞典例句
  • In constrast, exhaled smoke contains relatively large water droplets and appears white. 相反,从人嘴里呼出的烟则包含相当大的水滴,所以呈白色。 来自辞典例句
vi.翱翔,盘旋;徘徊;彷徨,犹豫
  • You don't hover round the table.你不要围着桌子走来走去。
  • A plane is hover on our house.有一架飞机在我们的房子上盘旋。
n.蒸汽,雾气
  • The cold wind condenses vapor into rain.冷风使水蒸气凝结成雨。
  • This new machine sometimes transpires a lot of hot vapor.这部机器有时排出大量的热气。
adj.不自然的,假装的
  • She showed an affected interest in our subject.她假装对我们的课题感到兴趣。
  • His manners are affected.他的态度不自然。
n.(工具的)柄,杆状物
  • He was wounded by a shaft.他被箭击中受伤。
  • This is the shaft of a steam engine.这是一个蒸汽机主轴。
v.旋转,打旋( swirl的现在分词 )
  • Snowflakes were swirling in the air. 天空飘洒着雪花。 来自《现代汉英综合大词典》
  • She smiled, swirling the wine in her glass. 她微笑着,旋动着杯子里的葡萄酒。 来自辞典例句
adj.累积的,渐增的
  • This drug has a cumulative effect.这种药有渐增的效力。
  • The benefits from eating fish are cumulative.吃鱼的好处要长期才能显现。
学英语单词
ADPS (automatic data processing system)
Almocarpine
ansa intestinalis
antiscolic
auriculo-acupuncture anesthesia
belly girt
blistering liquid
bossers
brake-field triode
brushings
Camberwell
camerals
CF&I
chapstick
check only for account
common antenna TV system
comparative statement
computer criminal
concentration polarization curve
concrete duct
conical bellows
copy of class certificate
Cormax
credit or debit notes
delegation of duties
dental sclerite
dentrite arm spacing
distributing oblique gear
door interlock switch
economic stages
electric hoistng
eligible bond
external behavior
fat combustion
feudal property
field-preacher
Fuente el Saz de Jarama
fungus resistance
general average letter of guaranty
general aviation flight plan
grade surface
gradient vector
grounding outlet
gumbs
hasselblad
hedous
Hedyotis cathayana
hemispherical emissivity
hermetic closure
hyalorisia tosaensis
increaseful
interrupt request latch
isosulfocyanic ester
knife turning tool
lash a hammock
like surd
linear-to-log converter
low-trusts
measles in beef
multiprocessing with a fixed number of tasks
musculus petrohyoideus
native-speaker
Ntdsutil
nyl
one-acters
osmium tetraiodide
pack-ins
Paederia foetida L.
paint industry
parting slide
plain weaves
pocke
podospora pauciseta
price of
procedural rights theory
production and efficiency
progressive education
psychoneurosis traumatica
R.M.L.
retransliteration
Rodiuran
scattered field
sci-fis
sectional mandrel
Selensulphur
semigovernmental
single-axle leading truck
sliding slot four bar linkage
slug two phase flow
sowldiour
spare details
stupefying
subacute severe hepatitis
test chart for children
took upon ourselves
towed pulvi-mixer
tuberculous empyema
unilateral conduction
upsetting machine
voltmetre
win easily
yente